Wideband High Efficiency 50 W GaN-HEMT Balanced Power Amplifier

This paper presents a wideband high efficiency GaN-HEMT balanced power amplifier for modern communication systems. Source- and load-pull analyses through simulations as well as pre-matching technique are applied to design the branch amplifiers. The matching networks comprise the 4:1 binomial impedance transformers to step down the $\mathbf{50}\ \Omega$ system impedance. Broadband SMD quadrature hybrid couplers are implemented to form the balanced configuration. The realized amplifier exhibits small-signal gain of $\mathbf{13.5}\pm \mathbf{2\ dB}$ over the target frequency range 1.3-3.6 GHz while maintaining well-matched conditions at both input and output. Large-signal measurements show that the amplifier properly deliver $\mathbf{47.5}\pm \mathbf{1.2\ dBm}$ continuous wave output power with an average power-added efficiency (PAE) of 55 % across the desired bandwidth.